File Format Signaling of Error Mitigation in Sub-Picture Bitstream Based Viewport Dependent Video Coding

2. The method of claim 1, wherein the track level mergable indications includes a track_mergable_with_other_video_tracks flag that, when set, indicates that the video bitstream carried in the current sub-picture track can be merged with one or more other of the plurality of video bitstreams carried in one or more other of the plurality of sub-picture tracks to generate a single video bitstream without decoding mismatch by rewriting only header data of the video bitstreams.

3. The method of claim 1, wherein the track level mergable indications are included in a track header box in a track box for each track containing one of the video bitstreams.

4. The method of claim 1, wherein the track level mergable indications are included in a track group box describing associations between the sub-picture tracks including the video bitstreams.

5. The method of claim 1, wherein the track level mergable indications are included in a media box describing track media information.

6. The method of claim 1, wherein the track level mergable indications, when set, further indicate that wavefront parallel processing is disabled by setting an entropy_coding_sync_enabled_flag to zero in picture parameter sets (PPSs) for the sub-picture tracks including the video bitstreams.

7. The method of claim 1, wherein the track level mergable indications are included in a track level box.

8. The method of claim 1, further comprising applying a multi-bitstream merge function to merge the sequences of sub-pictures into the spherical video signal for display via a viewport of a virtual reality rendering device.

9. The method of claim 8, wherein the multi-bitstream merge function is a lightweight merging function that does not change block level coding results for the sub-pictures.

10. The method of claim 1, wherein the sequences of sub-pictures are coded according to a High Efficiency Video Coding (HEVC) based viewport-dependent Omnidirectional Media Format (OMAF) video profile.

12. The video coding device of claim 11, wherein the track level mergable indications includes a track_mergable_with_other_video_tracks flag that, when set, indicates that the video bitstream carried in the current sub-picture track can be merged with one or more other of the plurality of video bitstreams carried in one or more other of the plurality of sub-picture tracks to generate a single video bitstream without decoding mismatch by rewriting only header data of the video bitstreams.

13. The video coding device of claim 11, wherein the track level mergable indications are included in a track header box in a track box for each track containing one of the video bitstreams.

14. The video coding device of claim 11, wherein the track level mergable indications are included in a track group box describing associations between the sub-picture tracks including the video bitstreams.

15. The video coding device of claim 11, wherein the track level mergable indications are included in a media box describing track media information.

16. The video coding device of claim 11, wherein the track level mergable indications, when set, further indicate that wavefront parallel processing is disabled by setting an entropy_coding_sync_enabled_flag to zero in picture parameter sets (PPSs) for the sub-picture tracks including the video bitstreams.

18. The non-transitory computer readable medium of claim 17, wherein the track level mergable indications includes a track_mergable_with_other_video_tracks flag that, when set, indicates that the video bitstream carried in the current sub-picture track can be merged with one or more other of the plurality of video bitstreams carried in one or more other of the plurality of sub-picture tracks to generate a single video bitstream without decoding mismatch by rewriting only header data of the video bitstreams.

19. The non-transitory computer readable medium of claim 17, wherein the track level mergable indications are included in a track header box in a track box for each track containing one of the video bitstreams.

20. The non-transitory computer readable medium of claim 17, wherein the track level mergable indications are included in a track group box describing associations between the sub-picture tracks including the video bitstreams.